What Is Wrong With This Program

Here's the Main Class called Question :

package com.test;

import java.util.HashSet;

public class Question {
 
 public static void main(String[] args) {
  
  HashSet uniqueObjects = new HashSet();
  
  TestObject obj1= new TestObject();
  obj1.setId(1);
  
  TestObject obj2= new TestObject();
  obj2.setId(1);
  
  uniqueObjects.add(obj1);
  uniqueObjects.add(obj2);
  
  System.out.println(uniqueObjects.size());
  
 }
 
 

}

Here's The TestObject Class :

package com.test;


public class TestObject {
 
 private int id ;
 
 
 @Override
 public boolean equals(Object other)
 {
  
  if (other == null)
   return false;
  if (other == this)
   return true;
  if (!(other instanceof TestObject))
   return false;
  
  TestObject otherObject = (TestObject)other;
  
  if(this.id == otherObject.getId())
   return true;
  
  return false;
 }


 public int getId() {
  return id;
 }


 public void setId(int id) {
  this.id = id;
 }

 
 
 
}

The program storing unique objects in the hash set , based on the id . Can you figure out what is wrong with this program and why ?